This invention relates to additives for polyester and vinyl aromatic polymeric compositions.
There is a need for more flexible corrosion-resistant resin products such as glass fiber/unsaturated polyester products and vinyl aromatic polymers. The brittleness of present corrosion-resistant isopolyesters is a drawback in the manufacture and subsequent handling of fiberglass tanks and pipes. Greater tensile elongation is an accepted criterion for the evaluation of such products. In polyesters, flexibility can be imparted to the resin by incorporating into the backbone of the polymer aliphatic dicarboxylic acids (e.g. adipic acid) or ether glycols (e.g. diethylene or dipropylene glycol), by reducing the degree of unsaturation or by using additives such as vinyl rubbers. Unfortunately, these methods suffer from inherent shortcomings such as higher cost, reduced corrosion resistance and a lower heat distortion temperature.
Flexibility also can be achieved by the addition of a plasticizer, however, generally these are not chemically bound within the crosslinked polymeric composition and thus can be leached from the gelled resin structure. An effective additive capable of imparting flexibility to unsaturated polyesters that cannot be leached from the resin would be of great interest to the industry. Further, an additive which also can impart toughness to a polyester or vinyl aromatic polymer would be useful in the industry.